In my prior U.S. Pat. Nos. 5,571,165, 5,733,324, and 5,824,033, which are incorporated herein by reference, I have disclosed disposable transcutaneous electrodes which are X-ray transparent and capable of conducting energy sufficient for defibrillation, as well as being capable of monitoring. These electrodes have an improved current density distribution between the electrode and the skin surface of the patient to efficiently deliver the energy without burning the patient's skin.
The patents more specifically disclose electrodes comprising a polymeric sheet member having an electrically conductive metal/metal chloride coating on a lower side thereof, a pad of electrically conductive gel underlying the polymeric sheet member, and a current distributing mat affixed to the sheet member and conductively connected to the metal/metal chloride coating. The current distributing mat is configured to be electrically conductive both along and transverse to the surface of the mat so as to transfer and distribute energy to the metal/metal chloride coating of the sheet electrode member. In one embodiment, the current distributing mat includes an open mesh metallized carbon fiber web having a carbon impregnated pressure sensitive adhesive composition on the upper and lower sides of the web. In a further embodiment, the current distributing mat comprises a conductive metal foil coated on its upper and lower sides with a conductive polymer adhesive.
The metal/metal chloride coated portion of the polymeric sheet member has an area sufficiently large to achieve adequate current density distribution between the electrode and the skin of the patient. The conductive mat has an area smaller than the area of the metal/metal chloride coating. The metal/metal chloride coating on the underside of the polymeric sheet has an outer perimeter that is configured to reduce the current density at the outer perimeter of the electrode member.
Electrical energy is conducted to or from the upper surface of the conductive mat and a medical device (i.e., a current generator and/or monitor). In applications where radio translucency of the wires is important, the wires may be advantageously formed of an X-ray transparent metal coated carbon fiber tow. For applications in which radio translucency of the conductors is not essential, the conductors may be multi-strand metal wires in which the strands can be spread out and bonded to the upper surface of the mat. Alternatively, a reinforced metallic tab or a metallic or conductive plastic post stud may be used for the conductor.
One of the difficulties in the manufacturing of electrodes, including those described above, has been the attachment of the current-carrying wire to the electrode body. Prior to the inventions disclosed in my above-identified patents, the standard method of wire attachment was a wire crimp connection to the current-carrying wire from the defibrillation equipment. While this method is still used by some manufacturers, its use is more likely to result in patient burns and an increased risk of failure of the defibrillation electrode. This was solved in the electrodes disclosed in my patents by utilizing the current distributing mat. The current distributing mat transfers normally high levels of electricity from the current-carrying wire through the electrode body and conductive gel so that the resultant electrode meets and exceeds all applicable AAMI and medical FDA standards. However, while this wire attachment method has proven to work very well, has been difficult to automate. The process of encapsulating the current-carrying wire and placing it on the electrode body is presently a hand process, which is both time consuming and expensive.
Accordingly, it is an object of the present invention to provide a medical electrode in which the current-carrying wire is secured thereto in a manner that both provides for an even current distribution and is susceptible to automation.